Thanks Howard.? I read your thread and it did sound similar.? Mind telling me what you tested on the Q508 123 mosfet?? So many threads with FET checking and voltage confirming and many have different voltages and, man, it's hard to keep up with all of them for us non-engineers.
Also going to check John Z's recommendations:
Checking the bias voltage to the mux usually provides a good test of 3253 health. It can be measured at a number of easily accessible points, such as any terminal of T401, or on C406. It should be approximately 2.5V relative to ground. Any reading that deviates significantly from that, up or down, is a strong indication of mux failure.
Thanks again
